In recent years, with the development of economy and the progress of society, the anti investigation awareness of criminals is also increasing, such as wearing gloves, destroying evidence and other criminal acts. Due to the influence of the law of unconsciousness and other factors, it often makes criminals leave contact traces unconsciously. In addition, due to the particularity of some cases, it is necessary to leave fingerprints on some important physical evidence. This paper mainly studies the development method of sweat fingerprints in field investigation. There are many ways to develop fingerprints in crime scene investigations. This paper mainly studies the development method of ninhydrin, which is widely used in the development of crime scene investigation fingerprint. The research of this paper is of great significance for the method to play an important role in crime scene investigation.